The present invention relates generally to abrasive tools used for drilling, cutting and grinding concrete, natural stone and other hard materials. More specifically, the present invention relates to a device that secures a plurality of abrasive segments to an abrasive tool and method for forming the device as well as replacing when worn.
A core bit is one type of abrasive tool that uses abrasive segments containing diamond to drill holes in concrete. A typical diamond core bit that can be used to drill holes in a concrete structure (e.g., a wall, floor, ceiling, column, bridge deck, etc.,) is produced by attaching individual diamond containing segments to the front face of a steel tube. The diamond core bit cuts a hole by using an electrical or hydraulic motor to spin the core bit around its axial axis, while at the same time being pushed forward either manually or by an automatic feeding mechanism to provide penetration. The drilling may be preferably done with coolant (e.g., water) but dry drilling may also be applied. In this manner of operation, an outside wall of a cylindrical opening is generated, while at the same time an inner core element is generated that detaches from the concrete structure once the diamond core bit has fully penetrated through the structure.
Eventually, the diamond segments become worn and have to be replaced. Replacing the diamond segments on a core bit is known as re-tipping the core bit. A typical re-tipping operation of a core bit will depend on how the diamond segments are secured to the front face of the steel tube. For example, the diamond segments may be brazed, laser welded or direct sintered to the front face of the steel tube. For the case of braze fitted diamond segments, a core bit user may de-braze the residues of the worn diamond segments from the face of the steel tube and braze fit new diamond segments to the same tube face. The steel tube with new diamond segments attached thereto may typically be shortened by a few millimeters as a result of this re-tipping operation. Shortening will only take place generally if the tube is cut up right behind the diamond segments in order to avoid the debrazing and this is typically only done in a repair shop. However, if the re-tipping operation is to be done directly on a construction site, then normally the only option is the debrazing and subsequent braze fitting of new segments. Overall, the re-tipping operation allows reduction in the costs associated with the core bit, which at the end reduces the cost of drilling holes in concrete and similar structures.